This could be related to what Gooberman experienced:Da Spadger wrote:So i was having fun deleting some unneeded vertices and this happened. After some further experimenting, it seems that deleting that lone vertex above and a little to the left makes things behave normally. Nope, didn't seem to make a difference now. Weird. (Grid size is at 4 in those pictures)
http://forum.zdoom.org/viewtopic.php?f= ... 20#p679098
It would be interesting to see if some algorithm can be developed, which could connect vertices in a meaningful way after the deletion of
multiple vertices, as in your case.
But is it worth the time and effort? Just simply deleting the linedefs and then connecting the left over vertices is simple enough.
[edit] added strike-through. I should have known better.